Process for chlorination,dehydrochlorination and purification of organic compounds

ABSTRACT

A process is provided for producing trichlorethylene, tetrachlorethylene or mixtures thereof including the steps of (1) reacting chlorine and ethylene in a liquid body containing predominantly chlorethanes, which chlorethanes have an average composition of at least 2.5 chlorine atoms per molecule; (2) maintaining the chlorethanes at a temperature in the range of 0* to 250* C.; (3) removing at least a portion of said chlorethanes and separating said removed material into a heavier product fraction containing a predominant amount of chlorethane having at least four chlorine atoms per molecule and a lighter fraction having an average chlorine content which is lower than that of said first fraction, the ratio of the number of mols of the heavier fraction to the number of mols of the lighter fraction being in the range of 1:0.1 to 1:30; (4) employing at least a portion of the said lighter fraction as liquid body in a subsequent chlorination reaction in accordance with steps (1), (2) and (3); and (5) dehydrochlorinating the heavier product fraction of step (3) by (6) maintaining the heavier product fraction at an elevated temperature in the liquid state while under positive pressure and in the presence of activated carbon.

United States Patent Kircher, Jr. et al.

[451 Sept. 12,1972

[72] Inventors: Charles E. Kircher, Jr., Detroit; Donald R. McAlister,Livonia, both of Mich.; Doris LeRoy Brothers,

Mason, Ohio [73] Assignee: Detrex Chemical Industries, Inc.,

Detroit, Mich. Y

[22] Filed: Oct. 6, 1969 [21] Appl. No.: 866,097

Related US. Application Data [63] Continuation of Ser. No. 638,468,May'15,

1967, abandoned, which is a continuation-inpart of Ser. Nos. 587,259,Oct. 17, 1966, abandoned, and Ser. No. 565,095, July 14, 1966, Pat. No.3,631,207.

[52] US. Cl. ..260/654 D, 260/654 H, 260/659 R [51] Int. Cl ..C07c 21/00[58] Field of Search ..260/654 H, 654 D, 660, 658

[56] References Cited UNITED STATES PATENTS 3,065,280 11/1962 Vogt..260/659 2,593,451 4/1952 Hill et al. ..260/654 3,299,152 1/1967 lnabaet a1. ..260/654 HCl 8 ETHYLENE H Primary Examiner-Leon Zitver AssistantExaminer-Alan Siegel Attorney-Paul & Paul [5 7] ABSTRACT A process isprovided for producing trichlorethylene, tetrachlorethylene or mixturesthereof including the steps of l) reacting chlorine and ethylene in aliquid body containing predominantly chlorethanes, which chlorethaneshave an average composition of at least 2.5 chlorine atoms per molecule;(2) maintaining the chlorethanes at a temperature in the range of 0 to250 C. (3) removing at least a portion of said chlorethanes andseparating said removed material into a heavier product fractioncontaining a predominant amount of chlorethane having at least fourchlorine atoms per molecule and a lighter fraction having an averagechlorine content which is lower than that of said first fraction, theratio of the number of mols of the heavier fraction to the number ofmols of the lighter fraction being in the range of 1:01 to 1:30; (4)employing at least a portion of the said lighter fraction as liquid bodyin a subsequent chlorination reaction in accordance with steps (1), (2)and (3); and (5) dehydrochlorinating the heavier product fraction ofstep (3) by (6) maintaining the heavier product fraction at an elevatedtemperature in the liquid state while under positive pressure and in thepresence of activated carbon.

8 Claims, 1 Drawing Figure 1 G C H 1 .1

T0 T0 T0 STORAGE STORAGE STORAGE 0R RERUN A HE T FRESH 8 E CARBON mHEAV'ES @SPENT CARBON HFAVIES CHLORINATION LIGHTS HEAVIES DEHYDRO-TRICHLOR- PERCHLOR- HEAVIES REACTOR DISTILLATION DISTILLATIONCHLORINATION ETHYLENE ETHYLENL DISTILLATION COLUMN COLUMN REACTORDISPRLkIIzTION DISHRLALISTION COLUMN ilBEM NAME LHloTmonwb PROCESS FORCHLORINATION, DEHYDROCHLORINATION AND PURIFICATION OF ORGANIC COMPOUNDSThis application is a continuation of our application, Ser. No. 638,468,filed May 15, 1967, now abandoned, which was a continuation-in-part ofour application, Ser. No. 587,259, filed Oct. 17, 1966, now abandoned,and our application, Ser. No. 565,095, filed July 14, 1966, now U.S.Pat. No. 3,631,207.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a continuous process for the production of trichlorethylene,tetrachlorethylene or mixtures thereof by the dehydrochlorination ofchlorethanes having at least four chlorine atoms per molecule, andparticularly to such a process wherein said chlorethanes have beenproduced by an improved chlorination process.

2. Description of the Prior Art One of the known methods fordehydrochlorinating polychlorinated ethanes consists of subjecting suchcompounds to a pyrolytic reaction in which they are heated to atemperature which is sufficiently high to cause dissociation intochlorinated olefin compounds and hydrogen chloride. Such hightemperature pyrolytic reactions usually involve passing a heated vaporover a heated bed as in the case of British Pat. No. 697,482, but it hasalso been proposed to use a heated surface immersed in a liquidchlorinated hydrocarbon as in the case of British Pat. No. 774,125. Ineither case, an elevated temperature of the order of 400-l ,200 C. atthe reaction surface is relied upon for the pyrolyticdehydrochlorination reaction. Somewhat lower reaction temperatures arepossible by dehydrochlorination in the vapor phase using a bed made upof activated carbon as in the case of U. S. Pat. No. 2,898,383.

An alternative dehydrochlorination method, which has been known for along time and which has been widely practiced commercially, comprisesreacting chlorinated ethanes with an inorganic alkaline chemical, suchas lime, or with organic bases, such as alkyl amines.

The use of metal chlorides has also been proposed for somedehydrochlorination reactions, but these reactions have not included thecommercial production of trichlorethylene and/or perchlorethylenebecause of undesirable side reactions.

While the known methods for dehydrochlorinating polychlorinated ethanesare capable of producing chlorinated ethylene products, they havecertain inherent disadvantages. In the prior art pyrolytic methods, theby-products formed during pyrolysis are carbonized at the elevatedtemperature of the reactor and this reduces the effectiveness of thereaction surface, thus requiring the use of even more heat until finallythe reactor must be taken out of service and the contaminated reactionsurface cleaned. Moreover, it is difficult to prevent decomposition ofthe desired dehydrochlorinated product within the reaction zone throughoverpyrolysis.

In the methods involving chemical dehydrochlorination by inorganicalkaline chemicals or organic bases, the hydrogen chloride which issplit off reacts with the inorganic alkaline chemical to form a chloridesalt or reacts with the organic base to form a hydrochloride salt.Consequently, the hydrogen chloride is not recovered in a useful form. Afurther disadvantage in the use of organic bases, such as triethylamineor quinoline, arises from the fact that some of the organic base iscontinuously lost in the reaction and such organic bases are expensive.When an organic base is used for dehydrochlorination, a salt thereof isformed with hydrogen chloride, which salt may or may not be economicallyrecoverable. Consequently their use in dehydrochlorination reactions isnot economically feasible. Moreover, where strong alkaline chemicals areused, further dehydrochlorination of the products may occur and this isparticularly undesirable. In the present invention the disadvantagespresent in the prior known dehydrochlorination methods applicable topolychlorinated ethanes have been overcome in a controlled process whichis capable of producing predetermined desired chlorinated ethyleneproducts together with hydrogen chloride in recoverable form fromcompounds selected from the group consisting of tetrachlorethanes andpentachlorethane or mixtures thereof at a cost which is competitive withany method now in commercial use for producing the correspondingdehydrochlorinated ethylenes, namely trichlorethylene andtetrachlorethylene. v

Highly. chlorinated ethanes such as the tetrachlorethanes andpentachlorethane are useful in the production of chlorinated olefinsolvents such as.

trichlorethylene and perchlorethylene, which solvents are of greatcommercial importance. However, the methods employed by prior workersfor the production of the tetrachlorethanes and pentachlorethane haveinvolved the use of costly and elaborate processing procedures and/orthe use of expensive reagents. For example, tetrachlorethanes have beenformed by the addition of chlorine to acetylene while pentachlorethanehas been formed by the dehydrochlorination of tetrachlorethane totrichlorethylene and chlorine I addition to the trichlorethylene.Despite prior work concerning the chlorination or ethylene, no processeshave been developed whereby a product predominantly comprised of thetetrachlorethanes, pentachlorethane or mixtures thereof were produced byethylene chlorination procedures.

Prior workers experimenting with the chlorination of ethylene haveobserved the formation of minor quantities of the highly chlorinatedethanes but have not successively developed techniques adapted for theproduction of these chlorethanes as the predominant products. For thepurpose of this invention, predominant products means that at leastpercent by weight, and preferably at least percent by weight of theproducts consist of chlorethanes having 4, 5 or 6 chlorine atoms permolecule.

SUMMARY OF THE INVENTION One of the objects of the present invention isto provide a process for producing trichlorethylene ortetrachlorethylene or mixtures thereof from symmetrical tetrachlorethanel,l ,2,2), asymmetrical tetrachlorethane (l,l,l,2), pentachlorethane ormixtures thereof.

A further object of this invention is to provide a process for producingtrichlorethylene or tetrachlorethylene or mixtures thereof from theabovementioned polychlorinated ethanes wherein the dehydrochlorinationprocess is carried out with the polychlorinated compound or compoundsbeing maintained under pressure in liquid phase and with thedehydrochlorination products being evolved within the liquid phase andon passing out of the liquid phase automatically form a vapor phasewhich contains hydrogen chloride, saturated chlorinated ethanes and theunsaturated chlorinated ethylenes resulting from the dehydrochlorinationreaction.

A still further object is to provide a process for producingtrichlorethylene or tetrachlorethylene .or mixtures thereof through acontrolled dehydrochlorination of a liquid polychlorinated ethanemixture of tetrachlorethanes or pentachlorethane, or both, maintainedunder a predetermined pressure and temperature, such as to produce ingood yields the desired chlorinated ethylene products and I-ICI.

It is another object of the present invention to provide a process forthe production of chlorethanes having at least four chlorine atoms permolecule, especially the tetrachlorethanes, pentachlorethane, andmixtures thereof.

It is another object of the invention to provide a process for theproduction of these chlorethanes by a reaction involving thechlorination of ethylene and less highly chlorinated ethanes.

It is another object of this invention to provide a process for theproduction of chlorethanes having at least 4 chlorine atoms per moleculewhich utilizes the chlorine reactant substantially completely.

Further objects will be apparent from the following description of theinvention.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a flow diagram ofapreferred embodiment ofthe process of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS We have discovered that theobjects set forth above are attained by a controlled process in whichcertain chlorinated ethanes are maintained in liquid phase and under apressure substantially in excess of atmospheric in the presence ofactivated carbon immersed therein, while supplying heat to control thetemperature of the liquid substantially above the temperature at whichl-ICI is evolved but below 300C. The process can be carried out as acontinuous process or as a batch process. By selecting the proper liquidphase composition containing predominantly the above-mentionedchlorinated ethane or ethanes and a feed stock composed of thesechlorinated compounds and by maintaining a predetermined temperature anda predetermined pressure, the process continuously produces apreselected chlorinated ethylene product or products and HCI inrecoverable form. In the case of tetrachlorethanes and pentachlorethanethis provides the great advantage of being able to operate the processto produce predominantly trichlorethylene or predominantlytetrachlorethylene or a mixture thereof in a predetermined ratio.Likewise, the process has the flexibility of operating on mixtures ofpolychlorinated ethanes or on individual polychlorinated ethanes.

In accordance with the present invention, the polychlorinated ethane isadmixed with carbon and subjected to liquid phase dehydrochlorination attemperatures of about C. to below 300 C., more preferably to 275 C., andmost preferably to 250 C.

It is important in the practice of the present process that thedehydrochlorination be carried out at temperatures from about 150 C. tobelow about 300 C. In systems involving the dehydrochlorination oftetrachlorethanes and pentachlorethane, severe catalyst deactivationtakes place at temperatures exceeding about 300 C., the deactivationbeing more severe the higher the temperature.

Surprisingly, the reaction of this invention is readily accomplished attemperatures below 300 C., even though the dehydrochlorination ofcompounds having chlorine attached to a primary carbon atom is involved.In this regard, the art teaches that with higher monochlorinated alkanesprimary chlorides will not dehydrochlorinate except at temperatures inexcess of 300 Contrary to such teachings, the compounds having chlorinesubstituted on a primary carbon atom which are reacted in accordancewith the process of the present invention have been found to undergodehydrochlorination readily and conveniently in liquid phase at muchlower temperatures. An outstanding advantage resulting from this is thatcatalyst life is improved.

During the dehydrochlorination, vapors comprising the polychlorinatedethane together with the dehydrochlorination products are evolved andare removed from the reaction zone.

It has been found that by operating in the prescribed manner outstandingresults are achieved. Exceedingly high reaction selectivities at goodreaction rates are attained while at the same time process costs areminimized and catalyst life is extended.

It is to be noted by way of contrast that in the previous vapor phasetechnology such reaction system control could not be achieved except ina limited way be decrease in process conversion.

In addition to the above, practice of the invention has other advantagesas follows:

By carrying out the dehydrochlorination from a liquid phase rather thana vapor phase, the size of reactor required is greatly reduced and thenecessity of vaporizing and preheating the feed stream is avoided. Thisrepresents a saving in both investment cost and operating cost.

Since the dehydrochlorination reaction is endothermic and cannot proceedat a rate faster than the required heat can be supplied, a greatadvantage arises by operating with a liquid phase rather than a vaporphase since much higher rates of heat transfer into the liquid phase canbe obtained.

By dehydrochlorinating from a liquid phase, it is necessary to operateunder a total pressure greater than the vapor pressure of the liquidphase at the temperature of operation. Through the use of such operatingpressures, the l-lCl formed as a result of the dehydrochlorinationreaction is automatically available at the pressure of operation. Thismakes possible the removal and recovery of organic vapors from the HClby condensing them in a water or brine cooled condenser and makesavailable a purified HCl supply for industrial use at moderate to highpressure without the need for compression.

in carrying out the present invention, high concentrations of thepolychlorinated ethane and relatively low chlorinated ethylene productconcentrations are maintained in the liquid phase. This means that theactivated carbon is used to better advantage since the active surface ofthe carbon is in contact with the saturated compound to bedehydrochlorinated rather than the unsaturated product compound whichrequires no further activation.

A very important technical and economic advantage is that it is possibleto add and remove incremental quantities of activated carbon to thesystem without interrupting the continuous operation of the process.This capability is generally not present in the prior art vapor phasecarbon catalyzed processes. Since there is a gradual loss of activity ofactivated carbon during use in dehydrochlorination reactions, ultimatereplacement of the carbon is necessary. The ability to add and removecarbon while operating, and thereby maintain catalyst efficiency at amore or less constant level, has both technical and economic advantageover the prior art processes in which carbon efficiency steadilydeclines during its operating life.

The activated carbons used commercially in vapor phasedehydrochlorination processes consist of particles which, in most cases,would not pass through a U. S. standard 20-mesh screen. In order tominimize pressure drop across the catalyst in a fixed bed vapor phasereactor, the size of the carbon particles used is such that they wouldnot pass through a U. S. standard mesh screen. Since practically all ofthe active catalyst surface is associated with the extremely smalldiameter pores of the carbon structure which lie below the surface ofthe particle, it is necessary for the feed and product components todiffuse into and out of the pores of the carbon as thedehydrochlorination reaction proceeds. This vapor phase diffusion intoand out of the pores of the carbon is one of the rate limiting factorsof the operation. This serious limitation is almost completely obviatedin the present process since, by dehydrochlorinating in the liquidphase, the activated carbon catalyst can be finely divided so as to passthrough a U. S. standard screen of 325 mesh or finer, without anydisadvantage from a handling point of view. For a given weight ofcarbon, the smaller the particle size, the greater is the exposedsurface area and the greater is the exposed surface area for moleculesto diffuse into the internal pores of the carbon. Also, by placing theactivated carbon in the liquid phase, under moderate to high pressure,there is a positive driving force which tends to keep all of the poresof the carbon filled with the liquid to be dehydrochlorinated. A maximumuse of the catalytic surface of the carbon is thereby realized in thenew process whether fine or coarse carbon particles are used.

In accordance with the present invention, it has been found thatchlorethanes having predominantly at least four chlorine atoms permolecule can be produced by the following method:

l. Chlorine and ethylene are introduced into a liquid body ofchlorethanes, the said liquid chlorethanes containing an average of atleast 2.5 and usually at least three chlorine atoms per molecule; thechlorine being introduced at a rate of at least about 3 mols chlorineper mol ethylene reacted;

2. the liquid body is maintained at chlorination reaction conditionswithin the temperature range of from about 0 C. to less than about 250C. and within the pressure range of from atmospheric pressure to about500 p.s.i.g.;

3. a portion of the liquid body is removed and separated into achlorethane produce fraction having an average chlorine content of atleast four chlorine atoms per molecule and a second chlorethane fractionhaving an average chlorine content which is lower than that of a saidfirst fraction, the mo] ratio of the first fraction to the secondfraction being in the range l:O.l to 1:30, and usually in the rangel:O.l to 1:19;

4. preferably all but at least a portion of the said second fraction isused in the liquid body in subsequent chlorination;

5. the chlorethane product having an average chlorine content of atleast four chlorine atoms per molecule is recovered from the chlorethaneproduct fraction of step 3.

By the above procedure it has been found that highly chlorinatedethanes, e.g., ethanes having four to six chlorine atoms per moleculecan conveniently be produced in a simple and straight-forward manner.Thus, using relatively inexpensive charge materials it is possible toprepare tetrachlorethanes, pentachlorethane and mixtures of theseproducts for dehydrochlorination in accordance with the process of thisinvention.

Throughout the present specification the production of tetrachlorethanesis described. Normally, symmetrical tetrachlorethane, CHC1 CHCl andasymmetrical tetrachlorethane, CCl;,CH C1, are formed in about equalamounts. However, where significant quantities of pentachlorethane arealso formed, the amount of asymmetrical tetrachlorethane predominatesslightly relative to the symmetrical tetrachlorethane due to thesomewhat faster reaction rate of symmetrical tetrachlorethane withchlorine to form pentachlorethane. Normally the asymmetrical tosymmetrical tetrachlorethane ratio will be from about 1:1 to about 3:2.

In accordance with the present invention, the chlorination reaction iscarried out at temperatures generally under 250 C., preferably in therange of from about 50 C. to about 200 C., and more preferably fromabout C. to about l50 c.

It is necessary that the reaction be carried out in the liquid phaseand, accordingly, pressure in the reaction zone should be sufficient tomaintain the liquid phase. Pressures broadly in the range of fromatmospheric pressure to about 500 p.s.i.g. are suitable, while morepreferred pressures are in the range of from about 25 p.s.i.g. to about250 p.s.i.g., and most preferably the pressure is maintained within therange of from about 50 p.s.i.g. to about p.s.i.g.

In a particularly preferred mode of operation, the exothermic heat ofchlorination is removed at least in part by continuously vaporizing partof the reaction liquid during the chlorination, removing the vaporsoverhead, condensing the chlorethane content of said vapors andreturning this condensate to the reaction zone. Other cooling means suchas the provision of indirect heat exchange in or outside of the reactionzone can be employed, preferably in conjunction with the partialvaporization techniques above described.

As an essential aspect of practice of the present invention, thecomposition of the liquid body of chlorethanes in the chlorination zonemust be such that the average chlorine content is at least 2.5 atoms ofchlorine per molecule of chlorethane. In a continuous system thiscomposition of the liquid body is maintained throughout the reactionwhereas in a batch system the liquid body has this composition at leastduring the last stages of the chlorination. The maintenance of such aliquid composition is necessary in order that the production of thedesired highly chlorinated ethane products be achieved. As anotherimportant consideration, in order to sustain the desired production ofthe highly chlorinated ethane products, ethylene must be introducedtogether with chlorine into the chlorination zone. The total amount ofchlorine which is introduced will depend both on the composition of thenet feed to the reaction zone and upon the desired chlorination product,but must be at a rate of at least about 3 mols of chlorine per mol ofethylene which is reacted. Depending upon the composition of the feed,the chlorine should be introduced in amounts sufficient to provide forthe desired production of the particular highly chlorinated product orproducts desired. Also, sufficient ethylene must be added such that atleast 5 percent and preferably at least percent of the reacting chlorineundergoes addition reaction with the ethylene.

An important feature in the practice of the present invention is theavoidance in the chlorination zone of materials which are detrimental tothe desired production of the highly chlorinated ethane products. It hasbeen determined that compounds of iron, aluminum, mercury and oxygenhave a distinctly disadvantageous effect on the desired reaction, andthe presence of these materials in an amount sufficient to interferesignificantly with the reaction should be avoided. Frequently it isdesirable to operate with equipment which is non-ferrous. Specifically,reactors and other equipment constructed of non-ferrous materials, e.g.,nickel clad iron, lnconel, are particularly preferred in carrying outthe process of this invention. For the purpose of this invention, theamount of iron, calculated as ferric chloride should be less than about0:006 percent by weight of the liquid reaction body, preferably lessthan about 00015 percent by weight of the liquid reaction body. Bestresults are achieved where the amount ofiron is less than 0.001 percentcalculated as above.

An outstanding advantage of the process of this invention is that byproper process control an exceedingly broad range of productiondistributions can be obtained. For example, it is possible to obtain asproduct essentially only tetrachlorethanes or essentially onlypentachlorethane, or any desired ratio of these materials, or mixturespredominating in tetrachlorethanes and/or pentachlorethane andassociated with beta trichlorethane, or hexachlorethane, etc.Selectivities, adapted to a particular economic situation can beachieved by appropriate process regulation.

ln continuous processing, at appropriate conditions of temperature andpressure, the following are important considerations in a particularpractice of the invention:

1. For a particular product fraction composition, increased ratios ofrecycle to product give higher reaction selectivities, the limit onrecycle being the economics of a particular situation.

2. Changing the average chlorine content of the liquid body in thechlorination zone will change the product distribution, other thingsbeing equal. For example, recycle of a less chlorinated fraction willresult in the production of a less highly chlorinated product mixture.

3. At a given recycle ratio and for a given product distribution, thereaction selectivity can be increased by recycling a less chlorinatedstream. Conversely, at a given selectivity and product distribution therecycle ratio can be varied quite considerably depending upon thechlorine content of the recycle stream i.e., the more highly chlorinatedrecycle streams require higher recycle ratio at the same selectivity andproduct distribution.

The regulation of the process to achieve particular results will befurther illustrated subsequently by way of working examples.

Although the invention is especially adapted for continuous operation,batch procedures can also be employed.

Referring to the drawing, the chlorination reaction is carried out inthe chlorination reactor. Maintained in the chlorination reactor is aliquid mixture consisting essentially of chlorethanes and having acomposition such that there is an average of at least 2.5, and usuallyat least three chlorine atoms per molecule of chlorethane A chlorinestream A is introduced into the chlorination reactor in an amountsufficient to provide for the production of the desired product withinthe limitations heretofore expressed. An ethylene stream B is introducedinto the chlorination reactor, and a mixture of chlorethane lights whichhave been separated from the product fraction is returned to thechlorination reactor as lights recycle C.

In the chlorination reactor the various materials fed to thechlorination zone react to form the desired highly chlorinated ethaneproduct.

The composition of the total mixture fed to this reaction zone willdepend on the distribution of the chlorinated product. In order toproduce the desired tetrachlorethanes, pentachlorethane, and the like itis necessary that the chlorination in the chlorination reactor becarried out in a liquid mixture which contains a high chlorine content,i.e., in a mixture of liquid chlorethanes having an average of at least2.5 chlorine atoms per molecule.

The chlorination reaction is exothermic and the reaction heat is removedby a combination of cooling coils (not shown) and vaporization of partof the liquid chlorethane mixture. The vapor mixture of chlorethanestogether with HCl is removed from the reactor and may be taken off asshown. Some of this vapor mixture passes to a condenser wherein thechlorethanes are condensed and returned to the chlorination reactor. Thenon-condensed HCl vapors are passed through suitable pressure regulatingmeans (not shown) to conventional recovery procedures.

A reactor effluent D is continuously removed from the chlorinationreactor and passes through a reducing valve into the lights distillationcolumn. This reactor effluent contains both chlorethanes having four ormore chlorine atoms per molecule as well as chlorethanes having lessthan four chlorine atoms per molecule. The liquid mixture isfractionally distilled in the lights distillation column and there isrecovered a lighter fraction containing HCl vapor together withchlorethanes. A heavier chlorethane product fraction, said fractionhaving an average chlorine content of at least four chlorine atoms permolecule is separated as heavies still feed E, which fraction is furtherfractionated in the heavies distillation column. A dehydrochlorinatorfeed stream F is taken as a distillate from the heavies distillationcolumn, and depending upon the reaction conditions and the separationprocedure this feed stream can be tetrachlorethanes, pentachlorethanes,hexachlorethanes, or mixtures of some or all of these materials. i

The chlorethanes in the lighter fraction from the lights distillationcolumn are removed and passed to a condenser wherein the chlorethanesare condensed. HCl vapor passes to recovery as heretofore described. Aportion of the chlorethane condensate is refluxed to the lightsdistillation column while the net product of this material passes backto the chlorination reactor. The composition of this return chlorethanefraction as well as the amount of this fraction relative to the amountof the product fraction removed as heavies still feed is importantinsofar as successful operation of the process is concerned. It isessential that the composition of this return chlorethane fraction besuch that the chlorine content be less than that of the heavies stillfeed. In addition, for successful operation it is necessary that theratio of the return fraction (lights recycle C) to the product fractionbe on 21 mol basis in the range 0.l:l to 30:l,preferably 1:1 to 19:1.

The dehydrochlorinator feed stream F is passed as a liquid underpositive pressure into the dehydrochlorination reactor while supplyingheat to maintain the dehydrochlorination reaction. The pressure in thedehydrochlorinator is preferably maintained in the range of from about35 p.s.i.a. to about 300 p.s.i.a. Dehydrochlorination of the crackerfeed F takes place in the dehydrochlorination reactor givingtrichlorethylene, perchlorethylene and HCl as the main reactionproducts. The combined liquid and vapor stream leaving thedehydrochlorination reactor is cooled while still under pressure, theresulting condensed and cooled chlorinated organics passing as crackereffluent G into a series of distillation trains, resulting intrichlorethylene H, perchlorethylene I and heavier chlorinatedhydrocarbons such as tetrachlorethanes and pentachlorethane J streams tostorage or rerun.

It will thus be seen that broadly, the continuous process of thisinvention comprises a process for producing trichlorethylene,tetrachlorethylene or mixtures thereof which comprises the steps of:

l. reacting chlorine and ethylene in a liquid body containingpredominantly chlorethanes, said liquid body having an averagecomposition of at least 2.5 chlorine atoms per molecule;

2. maintaining said liquid body at a temperature in the range of 0 to250 C.;

3. removing at least a portion of said liquid body and separating saidremoved liquid body into a heavier product fraction containing apredominant amount of chlorethane having at least four chlorine atomsper molecule and a lighter fraction having an average chlorine contentwhich is lower than that of said first fraction, the mol ratio of theheavier fraction to the lighter fraction being in the range 1:01 to1:30;

4. employing at least a portion of the said lighter fraction as liquidbody in a subsequent chlorination reaction in accordance with steps (1(2) and (3); and

5. dehydrochlorinating the heavier product fraction of step (3).

The following examples illustrate the process of this invention.

EXAMPLE I Ethylene was continuously fed into a liquid-phase reactor at arate of L1 mols/hr., together with chlorine at a rate of 3.40 mols/hr.,and recycle stream at a rate of 2.97 mols/hr., said recycle streamhaving the following composition:

Compound Mol l,2-dichlorethane 7.26 l, l ,2-trichlorethane 51.86tetrachlorethanes 40.88 pentachlorethane NIL hexachlorethane NIL Totall00.00

Compound Mol l,2-dichlorethane 5.43 l,l,2-trichlorethane 38.80tetrachlorethanes 46.57 pentachlorethane 8.44 hexachlorethane 0.76

Total l00.00

The withdrawn stream was distilled in a multi-tray fractionation columnwith an overhead pressure of 17 p.s.i.a. and temperature of 265 F. and abottoms pressure of 22.6 p.s.i.a. and temperature of 325 F. The

overhead fractionation was condensed and recycled to the chlorinationzone as above indicated. The net product was recovered as the bottomsstream at the rate of 1.00 mols per hour and had a composition asfollows:

Compound Mol 7r 1,2-dich1orethane NlL 1,1 ,Z-trichlorethane NlLtetrachlorethanes 63.47 pentachlorethane 33.53 hexachlorethane 3.00

Total 100.00

This net product may readily be converted by dehydrochlorination at aproduction rate of 0.622 mols/hr. trichlorethylene and 0.329 mols/hr.perchlorethylene.

EXAMPLE 2 Ethylene was continuously fed into a liquid-phase reactor at arate of 1.05 mo1s/hr., together with chlorine at a rate of 3.62mo1s/hr., and a recycle stream at a rate of 3.85 mols/hr., said recyclestream having the following composition:

Compound Mol 94 1,2dich1orethane 5.19 1,1 ,2-trichlorethane 37.05tetrachlorethanes 57.76 pentachlorethane NlL hexachlorethane NIL Total100.00

ofdissolved HCl as follows:

Compound Mol 1,2-dich1orethane 4.12 1,1,2-trichlorethane 29.40tetrachlorethanes 54.79 pentachlorethane 10.66 hexachlorethane 1.03

Total 100.00

The withdrawn stream was distilled in a multi-tray fractionation columnwith an overhead pressure of 17 p.s.i.a. and temperature of 273 F. and abottoms pressure of 22.0 p.s.i.a. and temperature of 330 F. The overheadfractionation was condensed and recycled to the chlorination zone asabove indicated. The net product was recovered as the bottoms stream atthe rate of 1.00 mols per hour and had a composition as follows:

Compound Mol 1F 1,2-dichlorethane NIL 1,1.2-trich1orethane NILtetrachlorethanes 43.30 pentachlorethane 5 1.70 hexachlorethane 5.00Total 100.00

This net product may readily be converted by dehydrochlorination at aproduction rate of 0.424 mols/hr. trichlorethylene and 0.507 mols/hr.perchlorethylene.

EXAMPLE 3 Ethylene was continuously fed into a liquid-phase reactor at arate of 1.1 mols/hr., together with chlorine at a rate of 3.58 mo1s/hr.,and a recycle stream at a rate of 10.4 mo1s/hr., said recycle streamhaving the following composition:

Compound M01 71 1,2-dichlorelhane 4.91 1,1,2-trichlorethane 35.26tctrachlorethanes 59.83 pcntachlorethane NIL hexachlorethane NIL Total100.00

Vent gases containing unreacted ethylene, together with volatilizedchlorinated hydrocarbons and 1-1C1 were withdrawn and subjected tocondensation; condensed chlorinated hydrocarbons were returned to thereactor, and the net cooled gas consisted largely of unconvertedethylene and HCI made in the reactor. During this period, the reactorwas maintained at a temperature of 160 C. and at a pressure of 100p.s.i.g. Chlorine conversion was essentially complete and ethyleneconversion was approximately percent. Reactor contents were continuouslywithdrawn at the rate of 1 1.4 mols/hr. and had a composition, exclusiveof dissolved HCI, as follows:

Compound Mol 1,2-dichlorethane 4.48 1,1,2-trich1orethane 32.17tetrachlorethanes 58.50 pentachlorethane 4.67 hexachlorethane 0.18 Total100.00

The withdrawn stream was distilled in a multi-tray fractionation columnwith an overhead pressure of 17 p.s.i.a. and temperature of 273 F. and abottoms pressure of 22.0 p.s.i.a. and temperature of 331 F. The

overhead fractionation was condensed and recycled to the chlorinationzone as above indicated. The net product was recovered as the bottomsstream at the rate of 1.00 mols per hour and had a composition asfollows: 4

Compound Mol k 1,2-dich1orethane NIL 1.1,2-trichlorethane NlLtetrachlorethanes 44.67 pentachlorethane 3 .3 3 hexachlorethane 2.0

Total 100.00

This net product may readily be converted by dehydrochlorination at aproduction rate of 0.438 mols/hr. trichlorethylene and 0.523 mols/hr.perchlorethylene.

EXAMPLE4 Ethylene was continuously fed into a liquid-phase reactor at arate of 1.02 mols/hr., together with chlorine at a rate of 3.86mols/hr., and a recycle stream at a 'rate of 4.24 mols/hr., said recyclestream having the following composition:

Compound Mol 1,2-dichlorethane 3.98 1,1 ,Z-trichlorethane 28.43tetrachlorethanes 67.59 pentachlorethane NlL hexachlorethane NlL Total100.00

Compound 1,2-dich1orethane 3.22

l,l ,2-trichlorethane 23.00

tetrachlorethanes 58.90

pentachlorethane 13.35

hexachlorethane 1.53

Total Upon distillation to provide the amount of recycle stream notedabove, the net product was recovered at a rate of 1.00 mols/hr. and hada composition as follows:

Compound M01 71' 1,2-dichlorethane NlL 1,1 ,24richlorethane NlLtetrachlorethanes 22.07 pentachlorethane 69.93 hexachlorethane 8.00

Total 100.00

This net product may readily be converted by dehydrochlorination at aproduction rate of 0.216

14 mols/hr. trichlorethylene and 0.685 mols/hr. perchlorethylene.

EXAMPLES Ethylene was continuously fed into a liquid-phase reactor at arate of 1.02 mols/hr., together with chlorine at a rate of 3.86 mols/hr.and a recycle stream at a rate of 9.40 mols/hr., said recycle streamhaving the following composition:

Compound Mol l,2-dichlorethane 3.59 1,1,2-trichlorethane 25.64tetrachlorethanes 63 .33 pentachlorethane 7.44 hexachlorethane NIL Total100.00

Vent gases containing unreacted ethylene, together with volatilizedchlorinated hydrocarbon and HCl were withdrawn and subjected tocondensation; condensed chlorinated hydrocarbons were returned to thereactor, and the net cooled gas consisted largely of unconvertedethylene and HCl made in the reactor. During this period, the reactorwas maintained at a temperature of C. and at a pressure of 130 p.s.i.g.Chlorine conversion was essentially complete, and ethylene conversionwas approximately 98 percent. Reactor contents were continuouslywithdrawn at the rate of 10.4 mols/hr. and had a composition, exclusiveof dissolved HCl, as follows:

Compound Mol 1'4 1,2-dichlorethane 3.24 l, 1 ,2trichlorethanc 23.18tetrachlorethanes 59.36 pentachlorethane 13.45 hexachlorethune 0.77

Total 100.00

Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 1.00 mols/hr. and acomposition as follows:

Compound Mol 7r 1,2-dichlorethane N [L l, l ,2-trichlorethane NlLtetrachlorethanes 22.07 pentachlorethane 69.93 hexachlorethane 8.00

Total 100.00

This net product may readily be converted by dehydrochlorination at aproduction rate of 0.216 mols/hr. trichlorethylene and 0.685 mols/hr.perchlorethylene.

EXAMPLE 6 Ethylene was continuously fed into a liquid-phase reactor at arate of 1.02 mols/hr., together with chlorine at a rate of 3.82mols/hr., and a stream at a rate of 8.00 mols/hr., said recycle streamhaving the following composition:

Compound Mol 7r 1,2-dlchlorethane 3.89 1.1.2-triehlorethane 27.80tetrachlorethanes 68.31 pentachlorethane NlL hexachlorethane NlL Total100.00

Vent gases containing unreacted ethylene, together,

with volatilized chlorinated hydrocarbons and HCl were withdrawn andsubjected to condensation; condensed chlorinated hydrocarbons werereturned to the reactor, and the net cooled gas consisted largely ofunconverted ethylene and l-lCl made in the reactor. During this period,the reactor was maintained at a temperature of 130 C. and at a pressureof 130 p.s.i.g. Chlorine conversion was essentially complete, andethylene conversion was approximately 98 percent. Reactor contents werecontinuously withdrawn at the rate of 9.00 mols/hr. and had acomposition, exclusive of dissolved HCl as follows:

Compound Mol 7r 1,2-dichlorethunc 3.46 1,1 ,2-trichlorethanc 24.71tetrachlorethancs 63.26 pentachlorethane 8.07 hcxachlorethane 0.50

Total 100.00

Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 1.00 mols/hr. and had acomposition as follows:

Compound Mol 7r 1,2dichlorethane NlL 1,1 ,2-trichlorethane NlLtetrachlorethanes 22.91 pentachlorethane 72.59 hexachlorethane 4.50

Total 10000 This net product may readily be converted bydehydrochlorination at a production rate of 0.224 moles/hr.trichlorethylene and 0.711 mols/hr. perchlorethylene.

EXAMPLE 7 Ethylene was continuously fed into a liquid-phase reactor at arate of 1.02 mo1s/hr., together with chlorine at a rate of 3.65mols/hr., and a recycle stream at a rate of 4.24 mols/hr., said recyclestream having the following composition:

Compound M01 7r 1,2-dich1orethane 4.96 1,1,2-trichlorethane 35.42tetrachlorethanes 59.62 pentachlorethane NIL hexachlorethane NIL Total100.00

Compound Mol 7r Ll-dichlorcthanc 4.01 1,1,2-trichlorcthanc 28.66tctrachlorcthanes 55.99 pcntuchlorethanc 10.3) hcxachlorcthanc 0.95

Total 100.00

Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 1.00 mols/hr. and had acomposition as follows:

Compound M01 71 1,2-dichlorethane NIL 1,1,2-trichlorethane NlLtetrachlorethanes 40.55 pentachlorcthane 54.45 hcxzichlorethane 5.00

Total 10000 This net product may readily be converted bydehydrochlorination at a production rate of 0.397 mols/hr.trichlorethylene and 0.534 mols/hr. perchlorethylene.

EXAMPLE 8 Ethylene was continuously fed into a liquid-phase reactor at arate of 0.816 mols/hr. together with ethylene dichloride at a rate of0.20 mols/hr. and chlorine at a rate of 3.21 mols/hr. and a recyclestream at a rate of 2.07 mo1s/hr., said recycle stream having thefollowing composition:

Compound Mol 1,2-dichlorethane 7.72 1,1.2-trichlorethanc 55.18tetrachlorethanes 37.10 pentachlorethane NlL hexachlorcthane NIL Total100.00

Vent gases containing unreacted ethylene, together with volatilizedchlorinated hydrocarbons and l-lCl were withdrawn and subjected tocondensation; condensed chlorinated hydrocarbons were returned to thereactor, and the net cooled gas consisted largely of unconvertedethylene and HCl made in the reactor. During this period, the reactorwas maintained at a temperature of 120 C. and at a pressure of p.s.i.g.

Chlorine conversion was essentially complete, and ethylene conversionwas approximately 98 percent. Reactor contents were continuouslywithdrawn at the rate of 3.07 mols/hr. and had a composition, exclusivel I ,i-trichlorethane 20.27 tetrachlorethanes 66.49 pentachlotethane7.09 hexachlorethane 0.6l

Total of dissolved HCl, as follows:

Cmpmmd Upon distillation to provide the amount of recycle stream notedabove, the net product was recovered at a 1,2-dichlorethane 5.2l HMichlomhane 3722 rate of l 00 mols/hr and had a composition as followstetrachlorethanes 45 .47 pentachlorethane l0.00 Compound Moi khexachlorethane 1.30 Total l00.00

l,2-dichlorethane NIL l, l ,Z-trichlorethane 20.00 Upon distillation toprovide the amount of recycle lelfachlmethanes I 5 pentachlorethane75.00 stream noted above, the net product was recovered at ahexachloremane 5m rate of l .00 mols/hr. and had a composition asfollows: Total 100.00

Compound Molii This net product may readily be converted byltuicblorethane NIL dehydrochlorination at a production rate of 0.735l,l,2-tr1chlorethane NlL l h M h I h h h ,emcmmelhanes 6232 mo 5/ r.'perc oret yene, wit no trlc oret y ene pentachlorethane 3318 beingproduced. 'fiig 3% The results of Examples 1-9, are summarized in Tablel, where the results of Examples l-4 generally ind d1 b d b dicate theconglomerative effect of control of the d h g: P may e convelgeo productdistribution and selectivity by recycle; Exame l g g a pro rate 0 pleSgenerally shows the effect of recycle composition; mo 5 perc met yExample-6 generally shows the effect of increased total EXAMPLE 9recycle; Example 7 generally shows the effect of I product dlstrlbutlonon selectivity; Example 8 shows Ethylene was continuously fed a F -P theeffect of a separate feed of chlorinated hydrocarreactor at a rate of1.1 mols/hr., together wlth chlorlne be having two chlorine atoms permolecule; and at a rate of 3.65 mols/hr. and a recycle stream at a rateample 9 Shows the effect of causing a product distribw of 7.25 mol s/hr.,sald recycle stream havmg the follow- {ion including essentially noproduct having four mg composltlorlz chlorine atoms per molecule.

Compound M0156 The above Examples l-9 show that in the practice of theprocess in accordance with our invention, it is LZ-dichlorethane 4.03possible to produce a preponderance of tetrachlorethanes orpentachlorethane or a designated pemachlomhane mixture of both.Referring to Examples 4 and 5, it is hexachlorelhanel g seen that 1norder to attain the same product distribu- Tma tion, where the recyclestream contains more compounds having five chlorine atoms per molecule,addivem 83565 Comalmng reacted ethylene, together tional total recycleis required. Thu'san economic com- Wilh Volallllled chlormafedhydrocarbons f Hcl parison of total recycle cost versus distillationcost for were withdrawn and Subjected to condensatlon; conthe remgva] ofSuch compounds can be made Referdensed chlorinated hydrocarbons werereturned to the ring to Examples 4 and 6, the ff f increased tom]reactor, and the net cooled gas consisted largely of unrecycle i h sinceE l 6 h i h hi h convened ethylene and made "l reactortotal recycle,attains a higher selectivity for the same 8 p the reactor was malmamedat a 0 product'distribution, (i.e., four-Cl atoms and five-Cl Peratureof and at a pre ssure of 100 patoms per molecule only). Referring toExamples4 and Chlorme convels l0n was essentially complete, and 7, theeffect of product distribution on selectivity is ethylene conversion wasPP QW 90 P shown, since for example, Example 7 has a lighter ReaCIOfContents were Continuously wlflfdrawn at product distribution (four-Clatoms and five-Cl atoms), rate of 8.25 mols/hr. and had a composltlon,exclusive and f h Same total recycle shows a hi h l i i- OfdlSSOlvedC185 followsi ty. Example 8 shows the effect of an outside Compound M011 chlorinated hydrocarbon feed. Example 9 shows the effect of aproduction distribution in which there are no Lzmchlomhane 354 compoundshave four chlorine atoms per molecule.

TABLE 1 Example 1 2 3 4 5 r, 7 g 9 t ififi-iiigiil oi iiigiie- Nil .ilNil Nil Nil Nil Nil Nil 20.00 Tetrachlorethanes 03.41 43.30 44. e1 22.07 22. 07 22. 05 40.55 62.82 Nil Pentachorethane 33. 5:1 51.10 53.5300.93 00.03 72. 54 54. 45 33.18 15.00 Hexachlorethane 3.00 5.00 2.00 8.00 8.00 4.50 5.00 4.00 5,00

Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100,00 100,00

TABLE I Example 1 2 3 4 5 6 7 8 9 ncyn ta'aigmms 1,2-dichlorethane 7. 265. l9 4. 91. 3. 98 3. 59 3. 89 4. 96 7. 72 4. 03 1,1,2-trichlorethane-51.35 31.05 35. 20 23.43 25. 64 27.30 35. 42 55.13 20.31Tetrachlorethanes 40. ss 57. 1e 50. s3 s1. 50 03. 33 0s. 31 59. 02 37.10 15. 05 Pentachlorethane Nil 11 .11 Nil 1. 44 11 Nil Nil NilHexachlorethane Nil Nil i1 Nil Nil il Nil Nil Nil Torn 100.00 100.00100.00 100.00 100 00 100 00 100.00 100.00 100.00

Total 111015 of recycle 2. 97 3. 85 10. 4 4. 2i 9. 40 8.00 4 24 2.07 7.25

Feed:

Mols chlorine 3. 40 3. 62 3.58 3. 86 3. 86 3. 82 3. 65 3. 2l 3. 65 Molsethylene.... 1.10 1.05 1.10 1.02 1.02 1. 02 1. 02 .816 1.10 Ethylenecomet-st 90. 00 95. 00 90. 00 9s. 00 98.00 98.00 98. 00 98.00 90. 00111015 EDC 0.20

As has been hereinbefore described, ferric chloride lJl-"ichlomha"e k.b. f b ft M It 15 tetrachlorethanes 28.3 is nown as an in 1 l or 0 Su 51 u ion c onna ion. pemachlomhane 21 is known that anhydrous ferricchloride in concentrahexachlorethane NlL tions of at least 55 ppmreduces the ratio of chlorine to ethylene reacting to 2.0/1. It will beseen from the following Examples l0 and l 1, that if all feed andrecycle rates are held constant, that operating the process of thisinvention in the presence of 55 ppm ferric chloride in the reactor asopposed to 2 ppm thereof, causes the net production of materialscontaining 4 or more chlorine atoms per molecule to drop from 100percent to 30.5 percent.

EXAMPLE l0 Ferric Chloride Concentration Chlorine Rate Ethylene RateBelow 2 ppm 3.20 moles/hour LOO moles/hour This experiment is conductedat 50 C. under 1 atmosphere of pressure.

EXAMPLE 1 l Ferric Chloride Concentration 55 ppm wt. Chlorine Rate 3.20moles/hours Ethylene Rate L00 mole/hour Recycle Rate 0.82 mole/hourComposition of Recycle:

Mole 5i l.2.-clichlorethane 14.2 I, l l -trichlorethane 85.8tetrachlorethanes NIL Composition of Reactor Contents:

Mole it l.2-dichlorethane 23.8 1.1 .Z-tn'chlorethane 59.5tetrachlorethanes 15.5 pentachlorethane l.2 hexachlorethane NIL ChlorineConversion 62% Ethylene Conversion 99% Ration Chlorine/Ethylene Reacting2.0 Net Product Rate .99 mole/hour Net Product Composition:

Mole Z ll-dichlorethane 31.7

This example is also conducted at 50 C. under I atmosphere of pressure.

EXAMPLE l2 Dehydrochlorination of Symmetrical Tetrachlorethane Astainless steel pressure vessel having a charge port and vapor take-offwas fitted with a thermowell and thermostat and the vessel waspositioned within an electrically heated mantle controlled by thethermostat. lnto the pressure vessel about 50 grams of activated carbonof particle size 4 X 10 mesh were placed followed by about 1,500 gramsof s-tetrachlorethane l,1,2,2). The vessel was then purged with nitrogento displace the air. A product take-off line which contained therein anautomatic pressure control means including a control valve was thenconnected to the product vapor take-off port. The product take-off linewas extended to an absorption system for recovery of thedehydrochlorinated organic product and HCl Heat was then applied to themantle to bring the liquid symmetrical tetrachlorethane to a temperatureof 225 C. During the heating the pressure was permitted to increase to127 pounds per square inch absolute (p.s.i.a.). The heating mantle andthe automatic pres sure controller were adjusted to maintain thistemperature and pressure and to supply heat for dehydrochlorination.While operating under these conditions the liquid phase reaction mixturewas found to have about'8 by weight .trichlorethylene, whichpercentageremained; substantially the same throughout the dehydrochlorinationreaction. The ofi gases were absorbed and condensed for analysis of theHCl and organics. These were found to be HCl and trichlorethylene insubstantially equi-molar quantities plus tetrachlorethane. Under theconditions given about 40 percent of the OE gases by volume consisted ofHCl and trichlorethylene. The volume ratio of chlorinated ethyleneproduct to chlorinated ethane in the evolved gases was about 0.35. Theoff gases were condensed by absorbing the HCl in cold water. The coldwater then condensed the organics to a separate liquid phase which wasanalyzed using standard separation and analytical techniques.

EXAMPLES l3 of the 1,1 ,2,2 tetrachlorethane.However, a pressure ofAsymmetrical 149 p.s.i.a. was employed while the temperature wasmaintained at 225 C. These conditions resulted in a liquid phasereaction mixture containing 1,1,2

tetrachlorethane and about 8 percent by weight trichlorethylene. Thecondensed off gases were found to contain HCl and trichlorethylene inequi-molar quantities and l,1,1,2 tetrachlorethane. About 35 percent ofthe off gases consisted of HCl and tetrachlorethylene The volume ratioof trichlorethylene to tetrachlorethane in the evolved vapors was about0.27.

EXAMPLE 14 Dehydrochlorination of Pentachlorethane The method of Example12 was carried out using abut 1,500 grams of pentachlorethane in placeof 1,l,2,2 tetrachlorethane. The temperature was maintained at 225 C.and the pressure within the vessel was maintained at 76 p.s.i.a. Theseconditions resulted in a liquid phase reaction mixture containing about8 percent by weight tetrachlorethylene. The volume ratio oftetrachlorethylene to pentachlorethane in the evolved gases was about0.27 and the off gases were found to contain HCl and tetrachlorethylenein equi-molar quantities and pentachlorethane. About 35 percent of theoff gases consisted of HC1 and tetrachlorethylene.

EXAMPLE 15 Dehydrochlorination of a Mixture Tetrachlorethanes andPentachlorethane The method of Example 12 was carried out using about1,500 grams of a liquid mixture comprising 1,l,2,2 tetrachlorethane,1,l,1,2 tetrachlorethane and pentachlorethane. The temperature wasmaintained at 225 C. and the pressure was held at 127 p.s.i.a. Theseconditions resulted in a liquid phase reaction mixture containingapproximately 4 percent by weight of trichlorethylene and percent byweight of tetrachlorethylene. The evolved gases contained l-1Cltrichlorethylene, tetrachlorethylene and a mixture of the chlorinatedethanes. The volume ratio of the chlorinated ethylene compounds to thepolychlorinated ethanes in the evolved gases was about 0.35. The amountof trichlorethylene by volume was approximately the same as the amountof tetrachlorethylene by volume with the HCl being present in an amountequivalent to 1 mol for each mol of trichlorethylene and 1 mol for eachmol of tetrachlorethylene.

EXAMPLE 16 Dehydrochlorination of a Mixture Tetrachlorethanes andPentachlorethane The method of Example was carried out at a temperatureof 225 C. and the pressure was maintained at 183 p.s.i.a. Theseconditions resulted in a liquid phase reaction mixture containing about16 percent by weight of trichlorethylene and 5 percent by weight oftetrachlorethylene. The evolved gases contained the.

ratio of about 1.0.

Asymmetrical perature of 250 C. and a pressure of 197 p.s.i.a. Theseconditions resulted in a liquid phase reaction mixture containing about5 percent by weight of trichlorethylene. The evolved gases containedtrichlorethylene and asymmetrical tetrachlorethane in 4 a volume ratioofabout 0.14.

EXAMPLE l9 Dehydrochlorination of Tetrachlorethane The method of Example13 was carried out at a temperature of 200 C. and a pressure of p.s.i.a.The conditions resulted in a liquid phase reaction mixture containingabout 25 percent by weight of trichlorethylene. The evolved gasescontained trichlorethylene and asymmetrical tetrachlorethane in a volumeratio of about 1.1.

EXAMPLE 20 Dehydrochlorination of Pentachlorethane The method of Example14 was carried out at a temperature of 200 C. and a pressure of 43p.s.i.a. These conditions resulted in a liquid phase reaction mixturecontaining about 5 percent by weight of tetrachlorethylene. The evolvedgases contained tetrachlorethylene and pentachlorethane in a volumeratio of about 0. l 5.

EXAMPLE 21 Dehydrochlorination of Pentachlorethane The method of Example14 was carried out at a temperature of 250 C. and a pressure of 179p.s.i.a. These conditions resulted in a liquid phase reaction mixturecontaining about 26 percent by weight of tetrachlorethylene. The evolvedgases contained tetrachlorethylene and pentachlorethane in a volumeAsymmetrical EXAMPLE 22 Dehydrochlorination of a Mixture of Symmetricaland Asymmetrical Tetrachlorethanes The method of Example 12 was carriedout using about 1,500 grams of a mixture of l,l,2,2 tetrachlorethane and1,1,1 ,2 tetrachlorethane in equal amounts. by weight in place of the1,l,2,2 tetrachlorethane of Example 12. The temperature was maintainedat 225 C. and a pressure of 172 p.s.i.a. was maintained. Theseconditions resulted in a liquid phase reaction mixture containing about15 percent by weight of trichlorethylene. The evolved gases containedtrichlorethylene and tetrachlorethanes in a volume ratio of about 0.6. i

From the above examples, it will be seen that the weight percentage ofthe chlorinated ethylene products in the liquid phase undergoingdehydrochlorination may be controlled in the practice of the process ofthe present invention by means of the temperature-pressure relationship.This provides great flexibility to 'the process since there is anoptimum weight percentage for a given dehydrochlorination reaction, andwe have found there is an optimum range of such weight percentage in theproduction of both trichlorethylene and tetrachlorethylene. Fortrichlorethylene and tetrachlorethylene. this relationship betweenpressures and temperatures for various weight percentages is i]-lustrated in the following tables.

TABLE 11 Dehydrochlorination of Tetrachlorethanes to Trichlorethyleneoperating Operating Vapor Ratio Liquid Composition Tempera- PressureTrichlorethylene/ (Organics) ture C. p.s.i.a Tetrachlorethanes Weight 7:

trichlortetraethylene chlorethanes TABLE 111 Dehydrochlorination ofPentachlorethane to Tetrachlorethylene operating Operating Vapor RatioLiquid Compositions Tcmpera- Pressure Tetrachlorcthylene/ (Organics)ture C. p.s.i.a. Pentachlorethane Weight Tetra- Pentachlorchlorethyleneethane The above data demonstrates that by varying reaction conditionsthe ratio of chlorinated ethylene product to polychlorinated ethane inthe evolved vapors is varied as is the liquid composition. Generallyspeaking, when conditions are varied to provide the lower ratios, lessefficient heat utilization results and process costs tend to increase.At the higher ratios, costs tend to rise due to lessened efficiency inthe use of the activated carbon. As hereinabove described, mol ratios ofchlorinated ethylene compound to polychlorinated ethane in the gasesevolved from the dehydrochlorination reaction should be from about 0.01to about 100, preferably from about 0.05 to about 50, and mostpreferably from about 0.1 to about 10.

Maintenance of a specified ratio of unsaturated product topolychlorinated ethane in the evolved vapor in turn results inmaintaining a certain optimum concentration of unsaturated product inthe liquid phase.

For convenience and clarity, the present invention has been illustratedin the above examples as running continuously from a fixed initialcharge of starting material which is used u as the dehydrochlorinationprocess proceeds. in actual commercial operation the process may proceedin the same manner but the feed material is continuously introduced intothe reaction vessel at a rate corresponding to the rate ofdehydrochlorination. A small amount of reaction mixture containingsuspended used carbon is periodically withdrawn from the reactor and isreplaced by new activated carbon which may be added with the incomingfeed or may otherwise be introduced into the reaction vessel.

The following example is illustrative of the commercial continuousprocess referred to above.

EXAMPLE 23 heating jacket until the reaction mixture is heated to 225 C.and the pressure is permitted to rise to an operating pressure of 166p.s.i.a. This pressure is maintained by an automatic control valve inthe vapor drawoff line which permits the escape of cooled effluent gas.The gas stream entering the cooler-condenser has a composition of 0.33mol fraction l-lCl, 0.24 mol fraction trichlorethylene, 0.09 molfraction tetrachlorethylene and 0.34 mol fraction polychlorinatedethanes. 1n the cooler-condenser organics are condensed.

After separation from the HCl stream, the condensed organics areseparated by fractionation, polychlorinated ethylene product isrecovered and the polychlorinated ethanes are returned to the reactionvessel through the liquid inlet. For each pounds of polychlorinatedethylenes produced, a portion of the reactor fluid is removed through apressure control valve positioned in the liquid draw-off line. Thevolume thus withdrawn is the volume calculated to contain one-fourthpound of activated carbon for each 100 pounds of chlorinated ethylenesproduced. After separation from the liquid the .carbon may be discarded.A corresponding weight of fresh activated carbon is introduced into thepressure vessel through the liquid inlet. The liquid portion is strippedto separate the lights from the heavies (molecular weight abovepentachlorethane). The lights are returned to the reactor. Liquid feedmade up of new feed and recycled polychlorinated ethanes is added at arate corresponding to the dehydrochlorination rate and in proportion tothe trichlorethylene and tetrachlorethylene being produced. Heat issupplied through the jacket at a rate sufficient to maintain the systemtemperature substantially constant at 225 C. while also supplying theheat for maintaining the dehydrochlorination reaction as measured by theeffluent stream. The process thus provides l-lCl, trichlorethylene andtetrachlorethylene on a continuous and uniform basis without thenecessity of changing the operating conditions to offset changes in theactivated carbon.

A satisfactory activated carbon for use in the practice of the presentinvention is Pittsburgh Activated Carbon Type BL or Type BPL or theirequivalents. These products are made and sold by Pittsburgh ActivatedCarbon Company of Pittsburgh, Pa. The total amount of activated carbonin the system may, of course, be varied within wide limits, provided anadequate total activated carbon surface is immersed in the liquid phaseto provide a satisfactory rate of dehydrochlorination. The preferredrange is to 20 percent by weight and the particle size may vary from ascoarse as through 4 mesh and retained on mesh (4 X 10 mesh) to finerthan through 325 mesh. In most sizes, the activated carbon will be insuspension since the liquid phase is continuously agitated by the escapeof the product gases. However, in large scale operations this may besupplemented by mechanical agitation to insure uniformity. The productgases may be cooled by known cooling means while still substantially atoperating pressure to give a condensed organic phase low in RC1 and anHCl vapor phase low in organic content. HCl in this form is recoverableby known means and is available for other use at essentially operatingpressure. The condensed organic liquid phase is removed from the systemthrough a suitable control valve. The condensed organic liquid phase isfurther processed in known ways to obtain the individual purified andstabilized chlorinated ethylene products.

Where the processes of the present invention are run continuously toproduce one or more chlorinated ethylene products, the correspondingfeed materials are introduced in amounts corresponding to the amounts ofproduct removed per unit of time from the reactor. This therefore,premits steady state operation of the reactor. Since HCl is present inthe system, it is desirable to operate under essentially anhydrousconditions to avoid possible corrosion of the equipment.

In describing the present invention, several examples have been setforth in which specific operating conditions are specified wherebyparticular polychlorinated ethanes are dehydrochlorinated in liquidphase under conditions of elevated pressure and temperature to yieldchlorinated ethylene compounds and HCl. However, various changes andmodifications may be made in such operating conditions without departingfrom the scope of the invention, including the incorporation or presencein the feed of other polychlorinated ethanes such as dichloroethane andtrichloroethane.

EXAMPLE 24 ing composition:

Compound Mol 1,2-dichlorethane 12.28

1,1,2-trichloroethane 87.72 tetrachlorethanes NIL pentachlorethane NILhexachlorethane NIL Total 100.00

' Reactor contents were continuously withdrawn at the rate of 130.2mols/hr. and had a composition, exclusive of dissolved HCl, as follows:

Compound Mol 1,2-dichlorethane l 1.40 1,1.2-trichlorethane 81.47tetrachlorethanes 6.94 pentachlorethane 0.18 hexachlorethane 0.01

Total 100.00

Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 9.28 mols/hr. and had acomposition as follows:

Compound Mol l,2dichlorethane NlL 1,1,2-trichlorethane NILtetrachlorethanes 97.41 pentachlorethane 2 .56 hexachlorethane 0.03

Total 100.00

The tetrachlorethanes shown above consisted of 1,1,2,2-tetrachlorethaneand 1,1 ,1 ,Z-tetrachlorethane in a mol ratio of about 1:1. The aboveproduct stream was fractionated to separate out the lower boilingl,l,l,2-tetrachlorethane and obtain a mixture for dehydrochlorinationwhich had the following composition:

Compound Mol l,l,2,2-tetrachlorethane 95.0

pentachlorethane 5.0

Total 100.00

This net product stream which amounted to 4.76 mols/hr. was then fed toa dehydrochlorination reactor to produce the correspondingchlorethylenes as outlined below.

The feed stream containing approximately mol 1,l,2,2 tetrachlorethaneand 5 mol pentachlorethane was passed as a liquid under a pressure ofabout 1 l5 p.s.i.g. through a reactor containing BPL activated carbon (4X 10 mesh) while supplying heat to maintain the temperature of thereactor at about 220 C. Under these conditions dehydrochlorination ofthe tetrachlorethane and pentachlorethane took place givingtrichlorethylene, perchlorethylene and HCl as the main reactionproducts. The combined liquid and vapor stream leaving the reactor wascooled while still under pressure to about 20 C. The resulting condensedand cooled chlorinated organics were then removed from the systemthrough a pressure operated control valve. The cooled HCl gasessentially free of chlorinated organics was also removed from thesystem through a pressure operated control valve. Operating data aregiven in the following table:

Reaction temperature C 220 Reaction pressure p.s.i.g. l Wgt. ofactivated carbon used gm 50 Duration of run hrs. 60 Total mols fed 286Mols l,l,2,2 tetrachlorethane 43.2 reacted Mols trichlorethylene formed42.3 Mols pentachlorethane reacted 2.7 Mols perchlorethylene formed 2.6Mols HCl formed 45.3 Mol ratio-chlorinated ethylenes to chlorinatedethanes in product 0.l9

EXAMPLE 25 Using the procedure of Example 24, polychlorinated ethaneswere produced as follows: Ethylene was continuously fed into aliquid-phase reactor at a rate of 4.44 mols/hr., together with'chlorineat a rate of 14.12 mols/hr., and recycle stream at a rate of 13.99mols/hr., said recycle stream having the following composition:

Compound Mo] 71 1,2-dichlorethane 8.07 l,l ,2-trichlorethane 57.66tetrachlorethanes 34.27 pentachlorcthane NIL hexachlorethane NIL Total100.00

Vent gases containing unreacted ethylene, together with volatilizedchlorinated hydrocarbons and HCl were withdrawn and subjected tocondensation; condensed chlorinated hydrocarbons were returned to thereactor, and the net cooled gas consisted largely of unconvertedethylene and HCl made in the reactor. During this period the reactor wasmaintained at a temperature of 140 C. and at a pressure of 100 p.s.i.g.

Chlorine conversion was essentially complete and ethylene conversion wasapproximately 96 percent. Reactor contents were continuously withdrawnat the rate of 18.26 mols/hr. and had a composition, exclusive ofdissolved HCl, as follows:

Compound Mol 7r l,2-dichlorethane 6.19 [,1 ,Z-trichlorethane 44.19tetrachlorethanes 42.75 pentachlorethane 6.41 hexachlorethane 0.46

Total l00.00

. Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 4.27 mols/hr. and had acomposition as follows:

Compound M01 3% 1,2-dichlorethane NIL l. l ,2-trichlorethane NlLtetrachlorethanes 70.56 pentachlorethane 27.44 hexachlorethane 2.00

Total [00.00

The tetrachlorethanes shown above consisted of l, l,2,2-tetrachlorethane and l, l l ,2-tetrachlorethane in a mo] ratio ofabout 1:1. The above product stream was fractionated to separate out thehigher boiling hexachlorethane and obtain a mixture fordehydrochlorination which had the following compositron:

Compound Mol l, l ,2,2tetrachlorethane 36.0 I, l l ,2-tetrachlorethane36.0 pentachlorethane 28.0

Total 100.00

Reaction temperature C. 225 Reaction pressure p.s.i.g. l25 Weight ofactivated carbon used gm. 50 Duration of run hrs. 5] Total mols fed 225Mols of l,l,l.2 and l,l,2.2 tetrachlorethane reacted 41.5 Molstrichlorethylene formed 40.7 Mols pentachlorethane reacted 27.4 Molsperchlorethylene formed 26.8 Mols HCl formed 68.! M01 ratio-chlorinatedethylenes to chlorinated ethanes in product 0.37

EXAMPLE 26 Using the procedure of Example 24, polychlorinated ethaneswere produced as follows: Ethylene was continuously fed into aliquid-phase reactor at a rate of 2.36 mols/hr., together with chlorineat a rate of 9.33 mols/hr., and recycle stream at a rate of 25.89mols/hr., said recycle stream having the following composition:

Compound Mol l,2-dichlorethane 3.21 l,l,2-trichlorethane 22.96tetrachlorethanes 73.83 pentachlorethane NlL hexachlorethane NlL Totall00.00

tor containing BPL activated carbon (4 X 10 mesh) while supplying heatto maintain the temperature of the reactor at about 235 C. Under theseconditions dehydrochlorination of the pentachlorethane took place givingperchlorethylene and HCl as the main reaction products. Operating dataare given in the following table:

29 30 Vent gases containing unreacted ethylene, together S i temperature22 with volatilized chlorinated hydrocarbons and HCl iffiggfigfijfig'jggfgga 8m. 50 were withdrawn and sub ected to condensation; conu s rs.40 densed chlorinated hydrocarbons were returned to the il g'zg i reamed:2 reactor, and the net cooled gas consisted largely of un- 5 Mo:pfilahtlorethylene formed 55.5 Mo s ormed $5.9 converted ethylene andHCl made in the reactor. Dur- M ratioqhlminmed elhylenes w mg thisperiod, the reactor was maintained at a temchlorinated ethanes inproduct |.7 perature of 140 C. and at a pressure of 100 p.s.i.g. MPLE 27Chlorine conversion was essentially complete and ethylene conversion wasapproximately 98 percent. 10 Using the procedure of Example 24,polychlorinated Reactor contents were continuously withdrawn at theethanes were produced as follows: Ethylene was conrate of 28.21 mols/hr.and had acomposition, exclusive tinuously fed into a liquid-phasereactor at a rate of of dissolved HCl, as follows: 1.58 mols/hr., toether with chlorine at a rate of 5.02

8 l5 mols/hr., and recycle stream at a rate of 1.90 mo1s/hr., CompoundMo1% said recycle stream having the following composition:

1,2-dichlorethane 2.95 Compound Mol 1,1,2-trichlorethane 21.07tetrachlorethanes 67.93 pentachlorethane 7.64 lz'dldllorelhane [2'28hexachlorethane 0A] 1,1,2-trlchlorethane 87.72

Tom I00 00 tetrachlorethanes NIL pentachlorethane NIL hexachlorethaneNIL Total 100.00

Upon distillation to provide the amount of recycle stream noted above,the net product was recovered at a rate of 2.32 mols/hr. and had acomposition as follows: Y l reacted ethylene together with volatlllzedchlorinated hydrocarbons and HCl Compound M01 were withdrawn andsubjected to condensation; condensed chlorinated hydrocarbons werereturned to the l 7 h] h NIL reactor, and the net cooled gas consistedlargely of unf ff z z jzj NIL converted ethylene and HCl made in thereactor. Durtetrachlorethanes 1.90 ing this period, the reactor wasmaintained at a tem- 368 perature of 120 C. and at a pressure. of 100p.s.i.g. Tow] 10500 Chlorine conversion was essentially complete, andethylene conversion was approximately 98 percent. Reactor contents werecontinuously withdrawn at the The tetrachlorethanes Shown aboveconsisted of rate of 3.45 mols/hr. and had a composition, exclusive 1, 1,2,2-tetrachlorethane and 1,1 ,l,2-tetrachlorethane of dlssolved asfollows: in a mol ratio of about 1:1. The above product stream d wasfractionated to separate out the higher boiling hexachlorethane andobtain a mixture for l 2 d h h 77 I n u e 4 6 dehydrochlorination whichhad the following composiff i 'ig 'gj 4M0 10111 tetrachlorethanes 34.97pentachlorethane 8.74 hexachlorethane 1.12 Compound M01 7: Total 100.00

1, 1 ,2,2 tetrachlorethane 1.0 lfi i -3 Upon distillation to provide theamount of recycle Pent 22? 00:00 stream noted above, the net product wasrecovered at a rate of 1.55 mols/hr. and had a composition as follows:

This net product stream which amounted to 2.20 mols/hr. was then fed toa dehydrochlorination reactor to reduce the corres ondin chloreth lenesas out- P P g 1,1,2-trichlorethane NIL ill'led bClOW. tetrachlorethanes78.01

The fed stream consisting essentially of pengig tachlorethane (98percent) was passed as a liquid Tom 100100 under a pressure of about 240p.s.i.g. through the reac- The tetrachlorethanes shown above consistedof 1 l ,2,2-tetrachlorethane and 1,1 1 ,2-tetrachlorethane in a molratio of about 1:1. The above produce stream was fractionated toseparate out the higher boiling hexachlorethane and obtain a mixture fordehydrochlorination which had the following compositron:

Compound Mol 7r l,l,2,2-tetrachlorethane 40.0 l,l l .Z-tetrachlorethane40.0 pentachlorethane 20.0

Total 100.00

This net product stream which amounted to 1.51

mols/hr. was then fed to a dehydrochlorinationreactor Reactiontemperature C. 250 Reaction pressure p.s.i.g. 270 Wt. of activatedcarbon used gm. 50 Duration of run hrs. l Total mols fed 77 Mols ofl,l,l,2 and l,l,2,2 tetrachlorethane reacted 56.0 Mols trichlorethyleneformed 55.5 Mols perchlorethylene formed l4.8 Mols pentachlorethanereacted 15.0 Mols HCl formed 70.9 Moi-ratio chlorinated ethylenes tochlorinated ethanes in product l0.4

Having thus described our invention we claim:

1. A process for producing trichlorethylene, tetrachlorethylene ormixtures thereof which comprises the steps of:

l. reacting chlorine and ethylene in the absence of light in a liquidbody consisting essentially of chlorethanes, said liquid body having anaverage composition of at least three chlorine atoms per molecule;

2. maintaining said liquid body at a temperature in the'range of 0 toless than about 250 C.;

3. removing at least a portion of said liquid body and separating saidremoved liquid body into a heavier product fraction containingchlorethanes having an average composition of more than four chlorineatoms per molecule and a lighter fraction having an average chlorinecontent which is lower than that of said first fraction and at leastthree chlorine atoms per molecule the mo] ratio of the heavier fractionto the lighter fraction being in the range l:0.l to 1:30;

4. recycling at least a portion of the said lighter fraction as liquidbody in a subsequent chlorination reaction in accordance with steps l(2) and (3); and

5. dehydrochlorinating the heavier product fraction of step (3) at atemperature of from about C. to below 300 C. in the liquid state whileunder positive pressure and in the presence of a contact m terial consisin essentially of activated carbon.

2. The process of cl um 1, wherein a part of the activated carbon isremoved as a suspension in the liquid reaction mixture and replaced by acorresponding amount of fresh activated carbon without interrupting theprocess.

3. The process of claim 1, wherein the elevated temperature is not morethan about 250 C.

4. The process of claim 1, wherein the elevated temperature is in therange of from about C. to not more than about 250 C., and the positivepressure is in a the range offrom about 35 p.s.i.a. to about 300p.s.i.a.

5. The process of claim 1, wherein the heavier product fraction of step(3) is tetrachlorethane, in which the operating pressure of step (5) ismaintained in the range of from 67 p.s.i.a. to 356 p.s.i.a. and in whichthe recoverable reaction products consist primarily of trichlorethyleneand HCl.

6. The process of claim 1, wherein the heavier product fraction of step(3) is pentachlorethane, in which the operating pressure of step (5) ismaintained in the range of from 36 p.s.i.a. to 192 p.s.i.a. and in whichthe recoverable reaction products consist primarily oftetrachlorethylene and HCl.

7. The process of claim 1, wherein the activated carbon is maintained insuspension in the reaction liquid.

8. The process of claim 1 wherein step (5) is carried out at atemperature in the range of from about 150 C.. to not more than about250 C., wherein, the heavier product fraction of step (3) consists of atleast one polychlorinated saturated ethane selected from the groupconsisting of l,l,2,2 tetrachlorethane, l,l,l,2 tetrachlorethane,pentachlorethane and mixtures thereof, continuously removing vaporscomprised of HCl, said chlorinated ethylene and said polychlorinatedsaturated ethane, the mo] ratio of chlorinated ethylene topolychlorinated saturated ethane being maintained in the range of fromabout 0.1 to about 10, and recovering said chlorinated ethylene.

2. maintaining said liquid body at a temperature in the range of 0* toless than about 250* C.;
 2. The process of claim 1, wherein a part ofthe activated carbon is removed as a suspension in the liquid reactionmixture and replaced by a corresponding amount of fresh activated carbonwithout interrupting the process.
 3. The process of claim 1, wherein theelevated temperature is not more than about 250* C.
 3. removing at leasta portion of said liquid body and separating said removed liquid bodyinto a heavier product fraction containing chlorethanes having anaverage composition of more than four chlorine atoms per molecule and alighter fraction having an average chlorine content which is lower thanthat of said first fraction and at least three chlorine atoms permolecule the mol ratio of the heavier fraction to the lighter fractionbeing in the range 1:0.1 to 1:30;
 4. recycling at least a portion of thesaid lighter fraction as liquid body in a subsequent chlorinationreaction in accordance with steps (1), (2) and (3); and
 4. The processof claim 1, wherein the elevated temperature is in the range of fromabout 190* C. to not more than about 250* C., and the positive pressureis in the range of from about 35 p.s.i.a. to about 300 p.s.i.a.
 5. Theprocess of claim 1, wherein the heavier product fraction of step (3) istetrachlorethane, in which the operating pressure of step (5) ismaintained in the range of from 67 p.s.i.a. to 356 p.s.i.a. and in whichthe recoverable reaction products consist primarily of trichlorethyleneand HCl.
 5. dehydrochlorinating the heavier product fraction of step (3)at a temperature of from about 150* C. to below 300* C. in the liquidstate while under positive pressure and in the presence of a contactmaterial consisting essentially of activated carbon.
 6. The process ofclaim 1, wherein the heavier product fraction of step (3) ispentachlorethane, in which the operating pressure of step (5) ismaintained in the range of from 36 p.s.i.a. to 192 p.s.i.a. and in whichthe recoverable reaction products consist primarily oftetrachlorethylene and HCl.
 7. The process of claim 1, wherein theactivated carbon is maintained in suspension in the reaction liquid. 8.The process of claim 1 wherein step (5) is carried out at a temperaturein the range of from about 150* C.. to not more than about 250* C.,wherein, the heavier product fraction of step (3) consists of at leastone polychlorinated saturated ethane selected from the group consistingof 1,1,2,2 tetrachlorethane, 1,1,1,2 tetrachlorethane, pentachlorethaneand mixtures thereof, continuously removing vapors comprised of HCl,said chlorinated ethylene and said polychlorinated saturated ethane, themol ratio of chlorinated ethylene to polychlorinated saturated ethanebeing maintained in the range of from about 0.1 to about 10, andrecovering said chlorinated ethylene.